When apparatuses connected through a network mutually perform packet transmission and reception, an apparatus of a transmission source (hereinafter referred to as “source apparatus”) may acquire an address of an apparatus of a transmission destination (hereinafter referred to as “destination apparatus”) prior to transmission of the packet with data stored therein (hereinafter referred to as “data packet”).
Patent Literature (PTL) 1 discloses acquiring of a MAC address of a destination apparatus by a source apparatus using an ARP (Address Resolution Protocol). In Patent Literature 1, the source apparatus that does not know the MAC address of the destination apparatus transmits a broadcast packet including an IP address of the destination apparatus. The apparatus to which the IP address included in the broadcast packet is assigned transmits a response packet including the MAC address of its own apparatus to the source apparatus. With this arrangement, the source apparatus can acquire the MAC address of the destination apparatus.
On the other hand, there is provided a centralized control type network path control method where control over a packet forwarding path using a plurality of nodes is concentratedly performed by a control apparatus. As an example of the technology of such a centralized control type, there is provided an OpenFlow (OpenFlow) technology.
Patent Literature 2 discloses a path control method of the centralized control type using the OpenFlow technology. In the OpenFlow technology described in Patent Literature 2, communication is regarded as an end-to-end flow, and path control, load distribution, and path optimization are performed on a per-flow basis.
Referring to Patent Literature 2, a switch that functions as a forwarding node includes a secure channel for communication with a control apparatus (also termed as “controller”) that calculates a packet path, and operates according to a flow table set by the control apparatus. In the flow table, a set of a matching rule to be matched against packet header information and an action defining processing content to be applied to a packet that matches the matching rule is defined. The action includes processing such as forwarding the packet to a specific interface.
When the switch described in Patent Literature 2 receives a packet from a terminal, the switch searches the flow table for a processing rule (flow entry) having a matching rule that matches header information of the received packet. When the processing rule (flow entry) that matches the received packet is found as a result of the search, the switch executes processing content forwarding the received packet to a specific interface) described in the action field of the flow entry.
On the other hand, when the flow entry that matches the packet is not found as a result of the search, the switch requests the control apparatus to set the flow entry for the received packet. The control apparatus calculates a path for the received packet and notifies the flow entry for implementing forwarding using the path to the switch related to the calculated path, in response to the request. The switch that has received the notification of the flow entry updates the flow table, and executes the processing content described in the flow entry in the updated flow entry, or executes forwarding of the received packet.